capriccio, caprice, capriccioso, capricieux, capricieuse—a short character piece, typically in a humorous, fanciful, or playful manner. The concept juxtaposes the improvisatory free-form fantasy against the more formal, "serious" and logically "worked-out" sonata forms.Within a caprice, the range of expression may well include the serious and dark as well as demanding extraordinary technical skills such as a prelude or etude.

piano quartet—a ensemble (work) comprising violin, viola, cello and piano. Most of the great Classical and Romantic composers produced one or more works for this combination of which many are masterworks of chamber music.

quartet, quatuor [F], quartett [G], quartetto [I]—ensemble or work for four players the most important examples being the string quartet and the piano quartet

ricercar, ricercare, ricercate, recercada—instrumental composition from the late Renaissance and early Baroque with a variety of meanings and types. Typically a "searching", exploratory piece in the manner of a prelude, toccata or fugue. Generally, an early type of fugue.